JPS6258073B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a cylindrical magnetic domain (hereinafter simply referred to as a bubble).
The present invention relates to a bubble element having a stretcher-type bubble detection section in a bubble transfer path that transfers a bubble using an in-plane magnetic field. Currently, the mainstream method for reading out signals from such field access type bubble elements is based on the magnetoresistive effect. In order to facilitate signal detection, it is common to extend the bubble at right angles to the transfer direction, and for this purpose, a plurality of chevron patterns or the like are lined up in the direction of bubble extension in a part of the transfer path of the detection section. A stretcher configuration is adopted.

As bubbles become smaller, the bias magnetic field area that can stretch and drive the bubbles decreases relative to other parts of the bubble element, so various measures have been taken, such as improving the pattern shape of the stretcher part. . These were mainly intended to raise the upper limit of the bias magnetic field that can drive stretched bubbles (hereinafter referred to as stretched domains).

However, as a stretcher, it is also necessary to lower the lower limit of the driving bias magnetic field of the stretched domain.

Since the lower limit of the bias magnetic field of the bubble element is determined by the maximum value of the lower limit of the drive bias magnetic field of various functional parts including the stretcher, major loop, minor loop, etc., the lower limit of the bias magnetic field of the bubble element is determined by the lower limit of the bias magnetic field of the bubble element. This is because if the lower limit of the bias magnetic field is the maximum value of the lower limits of the drive bias magnetic field of the component parts of the element, the lower limit of the drive bias magnetic field of the bubble element can be lowered by lowering the lower limit of the drive bias magnetic field of the stretcher.

The present invention has been made in view of these points, and its purpose is to lower the lower limit of the drive bias magnetic field of the stretcher without lowering the upper limit of the drive bias magnetic field, that is, to shift the drive bias magnetic field region of the stretcher to the low bias magnetic field side. The object of the present invention is to provide a bubble element that can be expanded to

Whereas the upper limit of the stretcher drive bias magnetic field is determined by the contraction of the stretched domain,
The lower drive bias field limit is often due to errors in which the stretched domains extend outside the pattern columns of the stretcher and enter adjacent pattern columns from outside the pattern.

That is, under a low bias magnetic field, the tip of the stretched domain extending outside the pattern column moves toward the pattern end of the adjacent pattern column, which has a lower potential, and the stretched domain straddles the two pattern columns.

Therefore, in order to suppress such errors, the shape of the pattern pillars constituting the stretcher should be the same except for the ends, and the shape of the pattern pillars should be the same on both the upper and lower sides of the pattern pillars, or in several steps at one end. The pattern shape may be arranged in such a shape that the stretching force of the domain becomes small.

The present invention is characterized in that the pattern shape at the end of the pattern column is such that the pattern apex angle at both the upper and lower ends or at one end of the pattern column is smaller than the pattern apex angle at the center of the pattern column. The domain stretching force at the ends of the pattern pillars is weakened, and the stretched domains do not extend from the pattern pillars to the outside of the pattern even in a low bias magnetic field, and in a high bias magnetic field, there is sufficient domain stretching force except at the ends of the pattern pillars. .

A more detailed explanation will be given below with reference to Examples. A thin film that suppresses hard bubbles by growing a YIG thin film of 700 Å on (YSmLuCa) ₃ (FeGe) ₅ O ₁₂ (film thickness 1.7 μm, characteristic length 0.18 μm, saturation magnetization 565 Gauss) grown on GGG as a bubble material. Above is a conventional chevron pattern with a pitch of 12 μm, a gap of 1 μm, a pattern width of 3 μm, and an apex angle of α ₁ 90°, as shown in Figure 1.
Figure 2 shows the transfer margin at a driving frequency of 100 KHz in the stretcher section of a magnetic bubble element in which 300 stages of stretchers are stacked in the direction of domain extension with 4000 Å of Al ₂ O ₃ interposed therebetween.

EXAMPLE A stretcher part ( _pattern column central part ₃₀₀ The steps have the same shape as the comparative example, 10 steps each at the top and bottom ends of the pattern column,
Figure 4 shows the transfer margin at a driving frequency of 100 KHz for a pattern shape in which the pattern apex angle _α2 is 80 degrees, and the spacing in the domain extension direction of the pattern at the top and bottom ends is not less than 1 μm. . In this embodiment, a chevron pattern is used as the stretcher pattern shape, but a chevron shape in which the pattern shape is deformed can also be used to obtain the same effect. As is clear from this example, according to the present invention, the lower limit of the drive bias magnetic field can be lowered without lowering the upper limit of the drive bias magnetic field in the stretcher section, which greatly contributes to expanding the drive margin of the magnetic bubble element. be.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the configuration of a conventionally known Chevron stretcher, Fig. 2 is a diagram showing the drive margin at 100KHz of the stretcher section of the configuration shown in Fig. 1, and Fig. 3 is a diagram showing the stretcher according to the present invention. FIG. 4 is a schematic diagram showing an embodiment of the structure, and FIG. 4 is a diagram showing a driving margin of the stretcher section in the embodiment of the present invention. α ₁ is the apex angle of the stretcher pattern of the comparative example and the pattern apex angle of the center part of the pattern column of the stretcher of the example, and α ₂ is the pattern apex angle of both ends of the pattern column of the stretcher of the example.

Claims (1)

[Claims] 1. Magnetic bubble domains can be extended in a direction perpendicular to the transfer direction of magnetic bubble domains on a part of the transfer path where magnetic bubble domains are transferred by an in-plane rotating magnetic field on a magnetic material capable of holding magnetic bubble domains. In a stretcher consisting of pattern columns with patterns arranged in the domain extension direction, the apex angle of the pattern at both the upper and lower ends or one end of the pattern columns arranged in the domain extension direction is the apex of the pattern in the center of the pattern column. A magnetic bubble element characterized by being smaller than a corner.